course," said Scanlon. "That _would_ be him, sure."

"To the unaided eye," proceeded Ashton-Kirk, "the scrapings seemed but
fragments of soil; but the lens showed me something more. Mixed with the
earth were some whitish particles--these," and he indicated one of the
little heaps of crumbled lime. "Association," and the investigator
looked at his friend steadily, "is one of the commonest faculties of the
mind. And as soon as I realized what the particles were, an idea took
shape."

"An idea," said Bat, with a feeling of uneasiness growing upon him.
"What sort of an idea?"

"True coincidence," said Ashton-Kirk, "is so infrequent an occurrence
that I seldom consider it. The presence of the lime upon the cellar
grating had no value, of course; but, as you know, a poker player will
sometimes retain cards in his hand which are worth nothing in
themselves, on the chance that he may draw certain others. And, once
these _are_ drawn, the heretofore valueless cards become of superlative
importance."

There was a pause; Bat Scanlon knew the weight of this illustration, and
sat in nervous expectation of what was to follow. "I had this idea in
mind when I stepped on the scaffolding outside Miss Cavanaugh's window,"
proceeded Ashton-Kirk. "The maid said the workmen had not been on the
job for some days, and so my search was not difficult. There were a
great many footprints, unquestionably of the mechanics; but on top of
these, plain and undisturbed, were the impressions of the 'creepers'
which I had seen in the sod at 620 Duncan Street."

"You are sure?" said Bat Scanlon, in a flat, throaty voice. "There's no
mistake?"

"Not any," replied the investigator, quietly.

Scanlon dropped the end of his cigar into a pewter bowl upon the table;
then he lighted another and lay back in his chair, his brows drawn
together in a heavy frown.

"All right," said he. "We'll let it go at that. There was a yegg of some
kind scouting around Nora's house; and the same lad also took some
observations of the place at Stanwick. We have that all settled. And now
what does it mean?"

Ashton-Kirk smiled.

"I don't know," said he. "But suppose we try to find out." He took the
telephone receiver from the hook and asked for police headquarters. In a
few moments he had the person required.

"Hello, Devlin," said he; "this is Ashton-Kirk."

"Oh, how are you?" came the big voice of Captain Devlin, of the
detective staff. "Osborne was just talking ab